Slashdot Mirror
Simple Comm Technique Beats Quantum Crypto
Atario wrote us with a link to a New Scientist article about an innovative new way of encrypting communications. An engineer at Texas A&M may have a way to exploit the thermal properties of a wire to create a secure channel. The result could be an effectively impenetrable way of securing communications, possibly outperforming quantum cryptography keys. "In their device, both the sender Alice and the receiver Bob have an identical pair of resistors, one producing high resistance, the other low resistance. The higher the total resistance on the line, the greater the thermal noise. Both Alice and Bob randomly choose which resistor to use ... Half the time ... they will choose different [resistances], producing an intermediate level of thermal noise, and it is now that a message can be sent. If Bob turns on his high resistor, and records an intermediate level of noise, he instantly knows that Alice has chosen her low resistor, in essence sending a bit of information such as 1 or 0. Kish's cipher does this many times, sending a random series of 1s and 0s that can form the basis of an encryption key, the researchers say."
But if I understand correctly, and I want to do this over ethernet, for example, that means that it is a) unroutable and b) my ethernet endpoints would have to be aware of my security preferences ?
Religion is what happens when nature strikes and groupthink goes wrong.
... or better: is Kish any electrical engineer ? ...
... . Furthermore, if Eve1 and Eve2 listen in a distance of only a few meters, they can auto-correlate the signal(s) and find the direction from which it travels. No, that is even simple, because the levels - as we know - are H and L. So the autocorrelation of H can be found out without much ado; either H travels right-to-left or left-to-right. Voilà. L doesn't disturb the autocorrelation function. Along the line, any line, higher spectral components are reduced; another rule all electrical engineers know: any practical system is by default a lowpass. When Eve1 and Eve2 simply record the signal, close to Alice and close to Bob, they can find out where the higher spectral components are to be found. Meaning, the sender of H is known.
...
To me, this whole matter with his formulae of the noise of a resistor is just hocus pocus; as much as the math is correct. But any reasonable electrical engineer knows these
What Kish rather seems to propose, is the injection of noise into a link; noise at two levels, nevermind if they are derived from a resistor, short-circuited or not, or any other noise generator.
Over. What he then says is the following:
If Alice sends high noise level ('H'), Bob will send low ('L') noise level; and vice versa.
The man-in-the-middle will have tri-state noise: LL,LH/HL,HH. LL and HH are out. The assumption in that paper, hidden behind a lot of barrage, is: LH and HL will appear identical to the eaves-dropper. Alice. however, when sending L, can pass an information quantum (since Bob will switch to H, knowing Alice sends L); while Alice sending H, Bob will switch to L, knowing Alice sends H).
The theory of Kish is, that Eve will have no clue if she intercepts HL or LH. Which only works in theory.
Because any electrical engineer deserving his title will tell you that those sources won't produce noise of identical spectrum in the first place. Therefore, the spectra will change, giving you a sequence of jumps. The maximum you have to do is toggling
Much ado about nothing, me thinks